Immunoreactivity of human cultured amniotic epithelial (AE) cells was investigated to evaluate the possible use of these cells as a transgene carrier in gene therapy for inborn errors of metabolism. AE cells were prepared and cultured by the methods described previously. Flow cytometry analysis revealed that these cells did not express any class II antigen at all on their surfaces. But the class I antigen was slightly expressed on their surfaces. Immunoperoxidase staining was slightly positive as to the class I antigen but not to the class II antigen at all. pSV-beta-galactosidase was transfected into AE cells by means of electroporation, followed by staining of the cells with X-gal. Several cells in 60 mm dish expressed beta-galactosidase activity. The possible gene transfer of beta-galactosidase into cultured AE cells may suggest that these cells could be used as a transgene carrier in gene therapy for inborn errors of metabolism.